184 PRACTICAL ORGANIC CHEMISTRY in a large round flask (i litre), and the contents of the flask well shaken. On the addition of the phenol, the liquid immedi- ately changes to a deep brown or black colour, and a heavy dark-br-own oil separates out. When the phenol has been added, the mixture is allowed to stand for 12 hours. The oil has by that time collected at the bottom of the vessel, and may be freed from acid by repeatedly decanting and pouring" in fresh water (three or four times). The contents of the flask consist of nearly equal quantities of para- and ortho-nitrophenol mixed with resinous products. In order to separate the two isomers, the product is distilled in a current of steam (sec Fitf. 68, p. 107) until the distillate is almost colourless. The ortho- compound distils in the form of a yellow oil, which may solidify in the condenser, in which event the water is temporarily run out of the condenser. The solid in the receiver is separated by filtration and dissolved in spirit at 40°, to which water is then added, drop by drop, until a turbidity is produced. Yield, i 5 grams. The solid residue contains the para-compound mixed with black, resinous substances, from which it is separated by repeatedly extracting with boiling water. The united portions of the aqueous extract are boiled with animal charcoal for half an hour in a large basin, and filtered through a fluted filler moistened with water. The filtrate is made alkaline with caustic soda solution, and concentrated to a small bulk (roo c.c.). If tarry matter separates, it must be filtered through a wet filter. To obtain the free para-compound, the concentrated aqueous solution of the sodium salt is cooled, and the separated sodium salt filtered. The crystals arc dissolved and acidified with concentrated hydrochloric acid, and the nitrophenol, whirh separates, is filtered and recrystallised from hot water. Yield, lo grams. Properties,—Q-NUrophcnol, sulphur-yellow needles, pos- sessing a peculiar smell ; m. p. 45°; b. p. 214" ; clistillable with steam ; soluble in alcohol, ether, and hot water ; less soluble in cold water. •^-Nitrophenol, colourless needles ; m. p. 114° ; easily soluble in alcohol and hot water ; slightly soluble in cold water. See Appendixi p. 295.